Independence of random variables with respect to a kernel and a measure #
A family of random variables is independent if the corresponding σ-algebras are independent.
Independence of families of sets and σ-algebras is covered in the Indep file.
This file deals with independence of random variables specifically.
Note that we define independence with respect to a kernel and a measure. This notion of independence
is a generalization of both independence and conditional independence.
For conditional independence, κ is the conditional kernel ProbabilityTheory.condExpKernel and
μ is the ambient measure. For (non-conditional) independence, κ = Kernel.const Unit μ and the
measure is the Dirac measure on Unit.
Main definition #
ProbabilityTheory.Kernel.iIndepFun: independence of a family of functions (random variables). Variant for two functions:ProbabilityTheory.Kernel.IndepFun.
A family of functions defined on the same space Ω and taking values in possibly different
spaces, each with a measurable space structure, is independent if the family of measurable space
structures they generate on Ω is independent. For a function g with codomain having measurable
space structure m, the generated measurable space structure is MeasurableSpace.comap g m.
Equations
- ProbabilityTheory.Kernel.iIndepFun f κ μ = ProbabilityTheory.Kernel.iIndep (fun (x : ι) => MeasurableSpace.comap (f x) (m x)) κ μ
Instances For
Two functions are independent if the two measurable space structures they generate are
independent. For a function f with codomain having measurable space structure m, the generated
measurable space structure is MeasurableSpace.comap f m.
Equations
- ProbabilityTheory.Kernel.IndepFun f g κ μ = ProbabilityTheory.Kernel.Indep (MeasurableSpace.comap f mβ) (MeasurableSpace.comap g mγ) κ μ
Instances For
Alias of the forward direction of ProbabilityTheory.Kernel.iIndepFun_congr.
Alias of the forward direction of ProbabilityTheory.Kernel.indepFun_congr.
Alias of the forward direction of ProbabilityTheory.Kernel.indepFun_iff_measure_inter_preimage_eq_mul.
Alias of the forward direction of ProbabilityTheory.Kernel.iIndepFun_iff_measure_inter_preimage_eq_mul.
Two random variables f, g are independent given a kernel κ and a measure μ iff
μ ⊗ₘ κ.map (fun ω ↦ (f ω, g ω)) = μ ⊗ₘ (κ.map f ×ₖ κ.map g).
If f is a family of mutually independent random variables (iIndepFun m f μ) and S, T are
two disjoint finite index sets, then the tuple formed by f i for i ∈ S is independent of the
tuple (f i)_i for i ∈ T.
Alias of ProbabilityTheory.Kernel.iIndepFun.indepFun_finset_sum_of_notMem.
Alias of ProbabilityTheory.Kernel.iIndepFun.indepFun_finset_prod_of_notMem.
Alias of ProbabilityTheory.Kernel.iIndepFun.indepFun_finset_sum_of_notMem₀.
Alias of ProbabilityTheory.Kernel.iIndepFun.indepFun_finset_prod_of_notMem₀.
The probability of an intersection of preimages conditioning on another intersection factors into a product.